Secure storage encryption system

ABSTRACT

A system for secure storage of data includes a key database and a processor. The processor is configured to receive a request associated with securely storing data and encrypt the tenant service key using a tenant master key. The data is encrypted using the tenant service key. The processor is further configured to encrypt the tenant master key using a customer key and store encrypted tenant service key and encrypted tenant master key in the key database.

CROSS REFERENCE TO OTHER APPLICATIONS

This application is a continuation of co-pending U.S. patent applicationSer. No. 15/252,051 entitled SECURE STORAGE ENCRYPTION SYSTEM filed Aug.30, 2016 which is incorporated herein by reference for all purposes.

BACKGROUND OF THE INVENTION

A critical feature for software applications is the ability to accessand modify repositories of data. The contents of a data repository cancontain sensitive information. For example, data for an employmentsoftware as a service application can include users' job titles, currentand previous employers, education, contact details, and otherinformation. A prerequisite for a secure data repository is the abilityto securely store the information by enforcing policies to manage theusers and the use of the data.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the invention are disclosed in the followingdetailed description and the accompanying drawings.

FIG. 1 is a block diagram illustrating an embodiment of a secure storagesystem.

FIG. 2A is a block diagram illustrating an embodiment of a securestorage system.

FIG. 2B is a flow diagram illustrating an embodiment of a process forstoring data securely.

FIG. 2C is a flow diagram illustrating an embodiment of a process forretrieving stored data securely.

FIG. 3A is a flow diagram illustrating an embodiment of a process forsecurely storing data.

FIG. 3B is a diagram illustrating an embodiment of a request objectmessage.

FIG. 4 is a flow diagram illustrating an embodiment of a process forsecurely storing data.

FIG. 5A is a flow diagram illustrating an embodiment of a process forsecurely storing data.

FIG. 5B is a diagram illustrating an embodiment of an unlock requestmessage.

FIG. 6A is a flow diagram illustrating an embodiment of a process forsecurely storing data.

FIG. 6B is a diagram illustrating an embodiment of an unlock responsemessage.

FIG. 7A is a flow diagram illustrating an embodiment of a process forauditing key releases.

FIG. 7B is table illustrating an embodiment of a release record.

FIG. 8A is diagram illustrating an embodiment of a KMS Encrypted KeyDatabase schema.

FIG. 8B is diagram illustrating an embodiment of a KMS Audit LogDatabase schema.

FIG. 8C is diagram illustrating an embodiment of a KRS Audit LogDatabase schema.

FIG. 9 is a flow diagram illustrating an embodiment of a process foraudit records.

FIG. 10 is a flow diagram illustrating an embodiment of a process foraudit records.

FIG. 11 is a flow diagram illustrating an embodiment of a process foraudit records.

FIG. 12 is a flow diagram illustrating an embodiment of a process foraudit records.

FIG. 13 is a block diagram illustrating an embodiment of a blockchain.

FIG. 14 is a block diagram illustrating an embodiment of a Merkle tree.

DETAILED DESCRIPTION

The invention can be implemented in numerous ways, including as aprocess; an apparatus; a system; a composition of matter; a computerprogram product embodied on a computer readable storage medium; and/or aprocessor, such as a processor configured to execute instructions storedon and/or provided by a memory coupled to the processor. In thisspecification, these implementations, or any other form that theinvention may take, may be referred to as techniques. In general, theorder of the steps of disclosed processes may be altered within thescope of the invention. Unless stated otherwise, a component such as aprocessor or a memory described as being configured to perform a taskmay be implemented as a general component that is temporarily configuredto perform the task at a given time or a specific component that ismanufactured to perform the task. As used herein, the term ‘processor’refers to one or more devices, circuits, and/or processing coresconfigured to process data, such as computer program instructions.

A detailed description of one or more embodiments of the invention isprovided below along with accompanying figures that illustrate theprinciples of the invention. The invention is described in connectionwith such embodiments, but the invention is not limited to anyembodiment. The scope of the invention is limited only by the claims andthe invention encompasses numerous alternatives, modifications andequivalents. Numerous specific details are set forth in the followingdescription in order to provide a thorough understanding of theinvention. These details are provided for the purpose of example and theinvention may be practiced according to the claims without some or allof these specific details. For the purpose of clarity, technicalmaterial that is known in the technical fields related to the inventionhas not been described in detail so that the invention is notunnecessarily obscured.

A system for secure storage of data is disclosed. The system comprises akey database and a processor. The processor is configured to receive arequest associated with securely storing data and encrypt a tenantservice key using a tenant master key. The data is encrypted using thetenant service key. The processor is further configured to encrypt thetenant master key using a customer key and store encrypted tenantservice key and encrypted tenant master key in the key database.

A system for secure retrieval of stored data is disclosed. The systemcomprises an encrypted key database and a processor. The encrypted keydatabase is configured to store an encrypted tenant service key and anencrypted tenant master key. The processor is configured to requestdecryption of the encrypted tenant master key into an unencrypted tenantmaster key. The decryption of the encrypted master key is approved by akey release system. The processor is further configured to decrypt theencrypted tenant service key using the unencrypted tenant master keyinto an unencrypted tenant service key and authorize a response to arequest using the unencrypted tenant service key.

A system for secure storage audit verification is disclosed. The systemcomprises a transaction pool and a processor. The processor isconfigured to verify a transaction stored in the transaction pool andsign a proposed block. The proposed block is based at least in part onthe transaction. The processor is further configured to receive acounter signed proposed block and add the counter signed proposed blockto a blockchain.

In some embodiments, the system stores data in a repository in a securemanner by encrypting the data using multiple keys. The repository datais encrypted using a tenant service key. The tenant service key is thenencrypted using a tenant master key. The tenant master key is encryptedusing a customer key. The encrypted tenant service key and encryptedtenant master key are stored in a key repository. The customer key isstored in a remote hardware security module. Decrypting the securerepository data requires decrypting the encrypted tenant master key withthe customer key, decrypting the encrypted tenant service key with thetenant master key, and finally decrypting the secure data with thetenant service key.

In some embodiments, the system comprises a key release system and a keymanagement system. The key release system is to release a customer keyenabling decryption of a tenant management key. The key managementsystem is to release a tenant service key enabling decryption ofrequested data. The key management system comprises an encrypted keydatabase and a processor. The encrypted key database is to store anencrypted tenant service key and an encrypted tenant master key. Theprocessor is to receive a request; request decryption of the encryptedtenant master key into an unencrypted tenant master key, wherein thedecryption of the encrypted master key is approved by the key releasesystem; decrypt the encrypted tenant service key using the unencryptedtenant master key into an unencrypted tenant service key; authorize aresponse to the request using the unencrypted tenant service key; andprovide the response to the request.

In some embodiments, the key management system additionally comprises anaudit database and a key management system engine. The audit database isto store a log of data encrypted and decrypted and the keys used for theencryption and decryption. The key management system engine is toreceive a request object; log information (e.g., a context) associatedwith the request object in the audit database; retrieve an encryptedtenant service key associated with the request object from the encryptedkey database; retrieve an encrypted tenant master key associated withthe encrypted tenant service key from the encrypted key database;generate an unlock request for the encrypted tenant master key; transmitthe unlock request to the key release system; receive an unlock responsein response to the unlock request (e.g., the unlock response includes atenant master key that has been decrypted using a customer key butencrypted (second encryption) using public/private key encryption fortransmission from the key release system to the key management system),extract a second encrypted tenant master key from the unlock request;decrypt the second encrypted tenant master key into an unencryptedtenant master key; decrypt the encrypted tenant service key using theunencrypted tenant master key into an unencrypted tenant service key;encrypt the unencrypted tenant service key into a second encryptedtenant service key; update the context with a key release authorizationin the audit database; generate a request response (e.g., providing thetenant service key enabling the decrypting of a requested data objectstored in a secure storage unit, providing the decrypted requested dataobject, securely providing the requested data object, etc.); andtransmit the request response.

In some embodiments, the audit database(s) stored in the system areverified or authenticated using a blockchain structure. In someembodiments, the blockchain structure checks that a recent, a prior, orall transactions stored in the audit database are valid.

In some embodiments, a system enables the secure storage and retrievalof data utilizing a key release system and a key management system. Forexample, a user can request to perform operations on encrypted datastored in a secure data storage by requesting the release of anencryption key by the key management system. In some embodiments, theuser is a human interfacing with a software application. In otherembodiments, the user is automated functionality of a softwareapplication or a software agent. In various embodiments, the data issecurely stored in an encrypted database. In some embodiments, eachinstance of a copy of customer data is a tenant and one or more servicesare provided for each tenant. For each service provided, the tenant hasan associated tenant service key used to encrypt that service instancedata. The tenant service keys are each encrypted with a tenant masterkey. The tenant master key is encrypted with a customer key.

In some embodiments, a request for the release of an encryption key tothe secure data is initiated by a user and sent to the key managementsystem in the form of a request object. The key management system enginereceives the release request for the encryption key. In someembodiments, the request object is a request for access to a tenantservice key. The key management system engine validates the request andlogs the context associated with the request into an audit database. Insome embodiments, the logged context comprises generating an auditrecord that is associated with key usage and key authorization. In someembodiments, the request object includes metadata identifying therequested tenant service key. Using the request object, an encryptedtenant service key and an encrypted tenant master key are retrieved. Insome embodiments, the encrypted keys are stored in an encrypted keydatabase.

In some embodiments, the key management system accesses a key releasesystem over a secure network connection and uses the key release systemto decrypt the encrypted tenant master key. The key management systemengine generates an unlock request for the encrypted tenant master keyand transmits the unlock request to the key release system. In someembodiments, the unlock request is based at least in part on theencrypted tenant master key. In the event the unlock request isaccepted, an unlock response is generated by the key release system andtransmitted to the key management system.

In some embodiments, the unlock request comprises the encrypted tenantmaster key and a customer key identifier. The key release systemextracts the unlock context and decrypts the encrypted master key usinga customer key corresponding to the customer key identifier. The keyrelease system encrypts the unencrypted tenant master key with a publickey associated with the key management system into a second encryptedtenant master key. In some embodiments, the unlock response comprisesthe second encrypted tenant master key.

In some embodiments, the unlock response received by the key managementsystem authorizes the key management system to use the tenant masterkey. In some embodiments, the unlock response received by the keymanagement system contains the second encrypted tenant master key (e.g.,the second encryption is for secure transmission from the key releasesystem to the key management system). The key management system extractsthe second encrypted tenant master key from the unlock response anddecrypts it using a corresponding private key associated with the keymanagement system. In some embodiments, the second encrypted tenantmaster key is cached at the key management system.

In some embodiments, the decrypted second encrypted tenant master key isused to decrypt the encrypted tenant service key. In some embodiments,the decrypted tenant service key is encrypted into a second encryptedtenant service key using a public key associated with the userrequesting access to the secure data storage. The key management systemengine updates the previously logged context with the key releaseauthorization. In some embodiments, the logged context comprises thesecond encrypted tenant service key. The key management system enginegenerates a request response that is transmitted to the user. In someembodiments, the request response indicates to the user that therequested access to the secure data storage has been granted and that aversion of the encryption key needed to access the secure data isavailable for retrieval. In some embodiments, the user retrieves thesecond encrypted tenant service key and decrypts it using the user'sprivate key. The user performs read and write operations on theencrypted data using the tenant service key (e.g., the decrypted secondencrypted tenant service key).

FIG. 1 is a block diagram illustrating an embodiment of a secure storagesystem. In the example shown, key release system 102 is connected to keymanagement system 104 via network 106. In some embodiments, key releasesystem 102 is managed by a customer and exists in the customer's datacenter. In other embodiments, key release system 102 is managed by athird party management service. Still in other embodiments, key releasesystem 102 is managed by a software as a service provider and the sameentity that provides key management system 104. In various embodiments,network 106 comprises one or more of the following: the Internet, awired network, a wireless network, a wide area network, a local areanetwork, or any other appropriate network or combination of networksthat allows secure network communication. The combination of key releasesystem 102 and key management system 104 connected via network 106allows a software provider to provide a customer access to a securestorage system and control over the release of the encryption keysneeded to access the secure storage system. In the scenario that thecustomer controls the key release system 102, the customer can revokeaccess to the secure data by denying key requests originating from keymanagement system 104.

FIG. 2A is a block diagram illustrating an embodiment of a securestorage system. In the example shown, key release system 202 isconnected to key management system 204 via network 206. In someembodiments, key release system 202 comprises key release system 102 ofFIG. 1; key management system 204 comprises key management system 104 ofFIG. 1; and network 206 comprises network 106 of FIG. 1. Key releasesystem 202 comprises key release system module (KRS Module) 232, keyrelease system audit database (KRS Audit DB) 234, hardware securitymodule (HSM) 236, and key release system audit agent (KRS Audit Agent)254. KRS Module 232 is connected to and can access KRS Audit DB 234 andHSM 236. KRS Module 232 is connected to KRS Audit Agent 254. HSM 236comprises a customer key 238. In some embodiments, HSM 236 secures oneor more customer keys. In some embodiments, HSM 236 and KRS Module 232are hosted in different data centers. In some embodiments, KRS Module232 is connected to one or more HSMs, each HSM comprising a customer keyfor each customer hosted on HSM 236. In some embodiments, KRS Module 232comprises key release module key (KRS Key) 233. In some embodiments, KRSKey 233 comprises a public/private key pair.

In some embodiments, key management system 204 comprises key managementsystem application programming interface gateway (KMS API Gateway) 222,key management system engine (KMS Engine) 224, encrypted key database(Encrypted Key DB) 226, key management system audit database (KMS AuditDB) 229, and key management system audit agent (KMS Audit Agent) 244.KMS Engine 224 is connected to KMS API Gateway 222, Encrypted Key DB226, KMS Audit DB 229, and KMS Audit Agent 244. In some embodiments,functionality of KMS API Gateway 222 is incorporated into KMS Engine 224and does not exist as a separate hardware component. In someembodiments, Encrypted Key DB 226 is a database that comprises encryptedkeys used to access secure databases. In some embodiments, Encrypted KeyDB 226 comprises encrypted tenant master key (Encrypted TMK) 227 andencrypted tenant service key (Encrypted TSK) 228. In variousembodiments, the number of encrypted keys corresponds to the number oftenants (customers or clients to a database software company) and thenumber of services offered. KMS Audit DB 229 is a database thatcomprises contexts associated with key requests. In various embodiments,the contexts are audit records to track requests for tenant service keysused to access secure databases. For example, KMS Engine 224 can readand write to Encrypted Key DB 226 including reading and writingencrypted keys stored in Encrypted Key DB 226. Upon retrieval of anencrypted key, the encrypted key is decrypted using the technologiesdiscussed herein. Once decrypted, the unencrypted key is used to decryptthe secure database. KMS Engine 224 can read and write to KMS Audit DB229 including writing, updating, and retrieving logged contextsassociated with key requests. In some embodiments, KMS Engine 224comprises key management system key (KMS Key) 225. In some embodiments,KMS Key 225 is a public/private key pair.

In some embodiments, management utility (MU) 212 is connected to securedatabase (Secure DB) 216 and secure database (Secure DB) 218. In variousembodiments, MU 212 is connected to multiple secure databases, eachdatabase securely storing data for one or more customers or tenants. MU212 comprises management utility key (MU Key) 214. In some embodiments,MU Key 214 is a public/private key pair. Secure database 216 and securedatabase 218 can each store data encrypted with different tenant servicekeys different from MU Key 214. For example, MU 212 is connected tosecure database 216 and secure database 218 but can not read or writedata stored securely in the attached databases without first retrievingthe appropriate encryption key from key management system 204. Invarious embodiments, MU 212 manages the lifecycle of software as aservice application and is accessed by an administrator user and/orcustomers.

In some embodiments, KRS Audit Agent 254 and KMS Audit Agent 244 areconnected via Network 206. KRS Audit Agent 254 interfaces with KRS AuditDB 234 and KRS Module 232. KMS Audit Agent 244 interfaces with KMS AuditDB 229 and KMS Engine 224. In some embodiments, KRS Audit Agent 254 andKMS Audit Agent 244 perform key release audits described in more detailbelow.

Security Protocols

In the example of FIG. 2A, the system relies on secure communicationprotocols. In some embodiments, the connections that traverse Network206, including connections between KRS Module 232 and KMS Engine 224 andbetween KRS Audit Agent 254 of key release system 202 and KMS AuditAgent 244 of key management system 204, use hypertext transfer protocol(HTTP) over transport layer security version 1.2 (TLS 1.2) over aninternet protocol security (IPSec) virtual private network (VPN) orsimilar appropriate protocols. In some embodiments, connections betweena key release system module and Hardware Security Modules, including theconnection between KRS Module 232 and HSM 236, use HTTP over Mutual TLS1.2 or similar appropriate protocols.

In some embodiments, connections to a database rely on a secure databaseconnection protocol. In some embodiments, the connections between KRSModule 232 and KRS Audit DB 234; between KMS Engine 224 and KMS Audit DB229; between KMS Engine 224 and Encrypted Key DB 226; between MU 212 andSecure DB 216; and between MU 212 and Secure DB 218 use Java™ databaseconnectivity (JDBC) over TLS 1.2 or similar appropriate protocols. Insome embodiments, read-only connections to a database are enforced byproviding database credentials that allow only read-only access. In someembodiments, the connections between KMS API Gateway 222 and KMS AuditDB 229; between KMS Audit Agent 244 of key management system 204 and KMSAudit DB 229; and between KRS Audit Agent 254 of key release system 202and KRS Audit DB 234 are read only and use JDBC over TLS 1.2 or similarappropriate protocols.

In some embodiments, connections between two networked components withinthe same datacenter, including the connection between KRS Module 232 andKRS Audit Agent 234 of key release system 202; between KMS Engine 224and KMS Audit Agent 244 of key management system 204, between KMS Engine224 and KMS API Gateway 222; and between KMS API Gateway 222 and MU 212,use HTTP over TLS 1.2 or similar appropriate protocols. In someembodiments, the connection between KMS Engine 224 and the user oradministrator of MU 212 uses secure/multipurpose internet mailextensions (S/MIME) or similar appropriate protocols.

In some embodiments, key release system 202 and key management system204 each exist in network isolation via a software or hardware firewall.In some embodiments, key release system 202 exists in the customerdatacenter. In some embodiments, datacenter boundary 208 defines theboundary of the datacenter for software as a service provider—Forexample, key management system 204, MU 212, Secure DB 216, and Secure DB218 reside within the datacenter of the software as a service provider.

FIG. 2B is a flow diagram illustrating an embodiment of a process forstoring data securely. In some embodiments, the process of FIG. 2B isimplemented using key release system 102 and key management system 104of FIG. 1. In the example shown, in 260 a request is received to storedata. In 262, the data is encrypted using a tenant service key. Forexample, a tenant service key is generated (e.g., randomly, usingentropy from an HSM, using a hash function of the data, or any otherappropriate key generation technique) and used to encrypt the data forsecure storage. In some embodiments, a MU encrypts the data using atenant service key generated by a KMS system. In some embodiments, theKMS system provides the tenant service key to the MU using a publicprivate key encryption and decryption. In some embodiments, the data isstored in a secure database. In 264, the tenant service key is encryptedusing a tenant master key. For example, a tenant master key is generated(e.g., randomly, using a hash function of the tenant service key, or anyother appropriate key generation technique) and used to encrypt thetenant service key for secure storage. In some embodiments, a request tothe KMS is received to encrypt and store data securely with the tenantservice key. In some embodiments, the KMS encrypts the tenant servicekey using a tenant master key. In 266, the tenant master key is causedto be encrypted using a customer key. For example, there is apre-generation step in which a customer creates a customer key inside ahardware security module, and the customer key is referenced using acustomer key ID. In some embodiments, the creation of a new tenantmaster key and the first request to encrypt it causes the customer KRSto pick a customer key ID/customer key to use, and then tells the KMSwhich customer key ID it used to encrypt the tenant master key. In someembodiments, a customer key is generated (e.g., randomly, using a lookuptable, or any other appropriate key generation technique by a KMSsystem) and used to encrypt the tenant master key for secure storage. Insome embodiments, the customer key is requested from a KRS system. Insome embodiments, the KRS key is received by a KMS system and used toencrypt the tenant master key. In some embodiments, the KRS systemcommunicates with the KMS system using public/private keycommunications. In some embodiments, the KMS system and the KRS systemare physically remote from each other. In 268, the encrypted tenantservice key and the encrypted tenant master key are stored in a keydatabase. In some embodiments, the encrypted tenant master key storagelocation and the encrypted tenant service key storage location arelogged in an audit database associated with the encrypted data storagelocation. In some embodiments, the customer key is stored in a hardwaresecurity module. In some embodiments, the hardware security module islocated remotely from the key database in a KRS system. In someembodiments, the customer key location or identifier is logged in anaudit database associated with the stored encrypted data storagelocation. In some embodiments, the tenant master key, the tenant servicekey, and the customer key or their identifiers are logged as well astheir locations. Symmetric encryption keys are generated inside thecustomer HSM 236, possibly prior to the secure data storage request,tenant master keys or tenant service keys generation. Keys are assignedidentifiers that are stored in both the customer HSM 236 and theencrypted key DB 226. The Customer encryption keys never leave thecustomer HSM, but the identifiers are passed along with requests toindicate which key shall be used in performing an encrypt or decryptoperation.

FIG. 2C is a flow diagram illustrating an embodiment of a process forretrieving stored data securely. In some embodiments, the process ofFIG. 2C is implemented using key release system 102 and key managementsystem 104 of FIG. 1. In the example shown, in 280 a request is receivedto retrieve data. In 284, an encrypted tenant master key and anencrypted tenant service key are retrieved from a key database. Forexample, an encrypted tenant master key and an encrypted tenant servicekey are retrieved from a key database based at least in part on datarequested to be retrieved. In some embodiments, the key database is partof a KMS system. A customer master key is determined based at least inpart on the data requested to be retrieved, e.g. the Tenant Master Keyneeded to perform the decryption. In some embodiments, the hardwaresecurity module is located remotely in a KRS system not physically localto a KMS system. In 286, the encrypted tenant master key is caused to bedecrypted using a customer key. For example, the encrypted tenant masterkey is caused to be decrypted using a customer key by sending a requestto a Customer HSM to perform decryption of the tenant master key. Insome embodiments, an encrypted tenant master key is decrypted afterbeing retrieved from the key database sent encrypted to the customer HSMand then returned in a decrypted format. In 288, an encrypted tenantservice key is decrypted using the decrypted tenant master key. In 290,the data is decrypted using the decrypted tenant service key. In someembodiments, the data decryption is logged in an audit databaseincluding the location of the tenant master key, the tenant service key,and the customer key used for the data decryption. In some embodiments,the tenant master key, the tenant service key, and the customer key arelogged as well as the locations.

FIG. 3A is a flow diagram illustrating an embodiment of a process forsecurely storing data. In some embodiments, the process of FIG. 3A isperformed by a management utility (MU) to request the release of atenant service key to access encrypted data. In some embodiments, theprocess of FIG. 3A is used by MU 212 of FIG. 2A. In the example shown,in 302 a MU generates a request object that indicates the nature of thetenant service key request. For example, the request object can comprisea request for a tenant service key and an optional request service type.In some embodiments, the request object comprises an x5c JavaScript™object notation (JSON) Web Token (JWT) signed with the private key ofthe MU. In some embodiments, the request object comprises a certificatewith a public key that is used for later processing. In someembodiments, the private key is the private key of MU Key 214 of FIG. 2Aand the certificate is the certificate associated with MU Key 214 ofFIG. 2A. In 304, the MU transmits a request object to the key managementsystem. In some embodiments, the request object can be verified byexamining the request object signature using a corresponding public key.In various embodiments, the signature is of the x5c JWT. In someembodiments, the key management system is key management system 104 ofFIG. 1. In some embodiments, the key management system is key managementsystem 204 of FIG. 2A. In some embodiments, the MU communicates to thekey management system via an application programming interface gatewaysuch as KMS API Gateway 222 of FIG. 2A.

In 306, the MU receives a request reply from the key management system.In some embodiments, the request reply is a confirmation that the keymanagement system received the request object. In some embodiments, therequest reply comprises a unique identifier associated with the requestobject. As one example, a unique identifier is a hash of the requestcontext for the tenant service key request and is generated by the keymanagement system. In some embodiments, step 306 is not performed andthe process proceeds from 304 to 312.

In 312, a request response is received. In some embodiments, the requestresponse is received by the MU. In some embodiments, the requestresponse is received by the user or administrator operating the MU. Therequest response indicates that the service request is ready to becompleted. The request response includes a unique identifier associatedwith the specific request. In some embodiments, the unique identifier isreceived with the request reply in 306. As one example, a uniqueidentifier is a hash of the request context. In some embodiments, therequest response is received by the user or administrator of the MU viaan email. In some embodiments, the request response is signed using anencryption key. As one example, the request response is signed using theprivate key associated with the key management system and can beverified using the corresponding public key. In some embodiments, theprivate key used to sign the request response is the private key of KMSKey 225 of FIG. 2A. In some embodiments, the transition from 306 to 312is asynchronous, meaning that the calling system does not wait for 306to complete, but instead holds a reference from 306 to check back lateron the status of the operation and is represented by the dotted line inFIG. 3A. In some embodiments, the process is blocked after 306 pendingapproval for the release of the requested tenant service key.

In 314, the MU confirms the key request to the key management system. Insome embodiments, the confirmation comprises presenting the uniqueidentifier associated with the request object to the key managementsystem. In various embodiments, the request is confirmed by transmittingto the key management system a new JWT signed using the private key ofthe MU. In some embodiments, the request confirmation is sent to the keymanagement system via an application programming interface gateway ofthe key management system.

In 316, the MU receives the encrypted tenant service key from the keymanagement system. In some embodiments, the tenant service key isdecrypted using a decrypted tenant management key. In some embodiments,the tenant management key is decrypted using a customer key that isreleased using a key release system. In some embodiment, the customerkey is cached for a session to enable decryption of a tenant managementkey for that session. In some embodiments, a tenant master key is cachedfor a session to enable decryption of a tenant service key for thatsession. In some embodiments, the encrypted tenant service key isencrypted using the public key of the MU. In some embodiments, thepublic key of the MU is the public key of MU Key 214 of FIG. 2A andincluded in the request object transmitted in 304. In 318, the MUdecrypts the encrypted tenant service key into an unencrypted tenantservice key. In some embodiments, the decryption relies on acorresponding private key such as the private key of MU Key 214 of FIG.2A. Using the unencrypted tenant service key, in 320, the MU performssecure data operations on a secure data storage. For example, the MU canperform read operations from the secure data storage by decrypting datastored on the secure data storage that is encrypted with the tenantservice key. As another example, the MU can perform write operations tothe secure data storage by encrypting the data using the tenant servicekey when writing to the secure data storage. In various embodiments, thesecure data storage is a database. In some embodiments, the encrypteddata is stored in one or more secure databases such as Secure DB 216 andSecure DB 218 of FIG. 2A. In some embodiments, the secure data storageis a hard drive, SSD, file cluster, or other appropriate storage medium.

In 322, the MU purges the unencrypted tenant service key. As an example,purging is accomplished by removing the unencrypted tenant service keyfrom memory. In some embodiments, the memory is overwritten with data toincrease the difficulty of recovering the unencrypted tenant service keyfrom memory. In some embodiments, the purging takes place based on apolicy setting. For example, the policy setting can include anexpiration time that indicates when the unencrypted tenant service keymust be purged. Once the unencrypted tenant service key is purged, theMU can no longer perform data operations on the secure data storagewithout initiating a new request for the appropriate tenant service key.

FIG. 3B is a diagram illustrating an embodiment of a request object. Insome embodiments, the request object of FIG. 3B is the request objectgenerated and transmitted in FIG. 3A and used to request a key release.In the example, a request object comprises client certificate 350,information context of the request, and a client signature. In someembodiments, Client Certificate 350 is encoded in base 64 and is thecertificate corresponding to MU Key 214 of FIG. 2A. In some embodiments,signature 357 is computed using the private key corresponding to clientcertificate 350. In some embodiments, signature 357 is computed over theheader and the base 64 encoding of the body of the message. In someembodiments, the private key used for signature 357 corresponds to theprivate key of MU Key 214 of FIG. 2A.

In some embodiments, the information context of the request comprisesfields Requested Key ID 351, Customer ID 352, Request Time 353, RequestNonce 354, Operation Context 355, and Operator Comment 356. In someembodiments, the information context contains an identifier for the keyrequested (e.g., Requested Key ID 351), a customer identifier (e.g.,Customer ID 352), the time of the request (e.g., Request Time 353), arequest nonce for the request (e.g., Request Nonce 354), detailedoperational context in the form of key/value pairs (e.g., OperationContext 355), and an operator comment (e.g., Operator Comment 356). Insome embodiments, the inclusion of suitably random Request Nonce 354ensures that messages cannot be replayed to initiate a key release morethan once. The key release system (KRS) keeps a cache of all recentlyused nonces. In some embodiments, the KRS comprises KRS 202 of FIG. 2Aor KRS 102 of FIG. 1. When a new request object message is received, thelocal nonce cache is checked so see if an entry exists already, and ifso, the message is rejected. If the KRS does not already track thenonce, it is recorded in the cache upon processing the request message.Nonces are purged from the KRS nonce cache after the validity period ofthe JWT used to secure the request object expires.

In some embodiments, operation context 355 comprises key/value pairsassociated with an operation key, an environment key, an affectedtenants key, and any other additional appropriate key. In someembodiments, the operation value associated with the operation keydescribes the purpose of the operation (e.g., to make a copy of thetenant, to migrate the tenant, etc.); the environment value associatedwith the environment key describes the operation environment, which iscomprised of a data center and designation of production ornon-production labels to indicate the type of data and workloadsexecuted in those tenants; and the affected tenants value associatedwith the affected tenants key is an array of tenants impacted by theoperation.

FIG. 4 is a flow diagram illustrating an embodiment of a process forsecurely storing data. In some embodiments, the process of FIG. 4 isperformed by a key management system (KMS) in response to a requestobject from a management utility (MU) for the release of a tenantservice key. In some embodiments, the process of FIG. 4 is used by keymanagement system 104 of FIG. 1 or key management system 204 of FIG. 2A.In some embodiments, the key management system includes an applicationprogramming interface gateway and the process of FIG. 4 is performedusing the KMS application programming interface gateway (KMS APIGateway) such as KMS API Gateway 222 of FIG. 2A. In some embodiments,partitioning the functionality of FIG. 4 into an application programminginterface gateway separate from other key management systemfunctionality limits the security risk to the key management system. Insome embodiments, the MU is MU 212 of FIG. 2A.

In the example shown, in 402 a KMS API Gateway receives a request objectthat indicates the nature of the tenant service key request. In someembodiments, the request object is transmitted to the KMS API Gatewayfrom 304 of FIG. 3A. In 404, the KMS API Gateway verifies the requestobject. In some embodiments, the KMS API Gateway verifies the requestobject by verifying the signature of the request object. As one example,the KMS API Gateway verifies the signature of the x5c JSON Web Token ofthe request object. In some embodiments, the verification uses a publiccertificate included with the request object. In some embodiments, thepublic certificate is Client Certificate 350 of FIG. 3B.

In 406, KMS API Gateway generates a request reply in response to therequest object. In some embodiments, the request reply includes a uniqueidentifier associated with the request object. As one example, theunique identifier is a hash of the request context for the tenantservice key request. In various embodiments, the unique identifier isused to reference a particular request object for a tenant service key.The use of a unique identifier allows the key management system toprocess multiple requests concurrently. Requests can originate from oneor more different management units for different customers, tenants, andservices. In 408, the request reply generated in 406 is transmitted tothe sender of the request object in 402. In some embodiments, therequest reply is transmitted to the management utility. In someembodiments the management utility is MU 212 of FIG. 2A.

In 410, the request object received in 402 is forwarded to a keymanagement system engine (KMS Engine). At this stage the key releaserequest has been verified and given a unique identifier before beingforwarded to the KMS Engine. In some embodiments, KMS Engine comprisesKMS Engine 224 of FIG. 2A. KMS API Gateway forwards the request objectto the KMS Engine to provide the KMS Engine context for the requestedrelease of a tenant service key. In 412, KMS API Gateway receives arequest confirmation corresponding to the request object from amanagement utility. In some embodiments, the request confirmation isinitiated because the management utility receives an out-of-bandnotification that the key release has been authorized. The requestconfirmation initiates the retrieval of the released key. In someembodiments, the transition from 410 to 412 is asynchronous andrepresented by the dotted line in FIG. 4. In some embodiments, therequest confirmation includes a unique identifier generated in 406 thatcorresponds to the request object received in 402. The unique identifieris used to identify a particular request for a tenant service key. Asone example, the unique identifier is a hash of the request context forthe tenant service key request and uniquely identifies a request. Insome embodiments, the request confirmation comprises a new JWT. In someembodiments, the request confirmation is signed with a private key andverified using the corresponding public key and/or certificate. Invarious embodiments, the certificate included in the request object isused to verify the request confirmation.

In 414, KMS API Gateway retrieves an encrypted tenant service key(Encrypted TSK). In some embodiments, the Encrypted TSK is stored in anaudit database. In some embodiments, the audit database comprises KMSAudit DB 229 of FIG. 2A. In some embodiments, the Encrypted TSK isencrypted using a public key and can only be decrypted using thecorresponding private key. In various embodiments, the public/privatekey is the public/private key associated with MU Key 214 of FIG. 2A. Insome embodiments, the public key is the public key of the certificateincluded with the request object received in 402.

In some embodiments, once the Encrypted TSK is retrieved from itsstorage location, the Encrypted TSK is permanently removed from thatlocation. As one example, after retrieving Encrypted TSK from KMS AuditDB, the Encrypted TSK is removed from KMS Audit DB. In some embodiments,KMS API Gateway messages KMS Engine to remove the record of theEncrypted TSK from KMS Audit DB. In some embodiments, the timing of whenthe record of the Encrypted TSK is removed is based on a policy setting.Once the Encrypted TSK and corresponding record expires a new keyrelease request must be initiated.

In 416, KMS API Gateway transmits the retrieved Encrypted TSK to the MU.The Encrypted TSK comprises an encrypted version of the requested tenantservice key requested by MU in the request object in block 402. Invarious embodiments, the tenant service key always exists in anencrypted format when passing through KMS API Gateway and can only bedecrypted using a private key accessible by the MU.

FIG. 5A is a flow diagram illustrating an embodiment of a process forsecurely storing data. In some embodiments, the process of FIG. 5A isperformed by a key management system (KMS) in response to an initialrequest object from a management utility (MU) for the release of atenant service key. In some embodiments, the process of FIG. 5A is usedby key management system 104 of FIG. 1 or key management system 204 ofFIG. 2A. In some embodiments, the key management system includes a keymanagement system engine (KMS Engine) and the process of FIG. 4 isperformed by the KMS Engine, such as KMS Engine 224 of FIG. 2A, inresponse to the forwarding of a request object by a KMS API Gateway. Insome embodiments, the MU comprises MU 212 of FIG. 2A.

In the example shown, in 502 a KMS Engine receives a request object thatindicates the nature of the tenant service key request. In someembodiments, the request object is transmitted from a KMS API Gateway tothe KMS Engine as described with respect to 410 of FIG. 4. In someembodiments, KMS API Gateway comprises KMS API Gateway 222 of FIG. 2A.In 504, the KMS Engine verifies the request object. In some embodiments,the KMS Engine verifies the request object by verifying the signature ofthe request object. For example, the KMS Engine verifies the signatureof the x5c JWT of the request object. In some embodiments, theverification uses a public certificate included with the request object.

In 506, the KMS Engine logs the context associated with the requestobject. In some embodiments, the KMS Engine logs the context to a keymanagement system audit database (KMS Audit DB). In some embodiments theKMS Audit DB comprises KMS Audit DB 229 of FIG. 2A and the context isstored as a database record. In some embodiments, the context logged isinformation associated with key usage and/or key authorization of therequested tenant service key. In some embodiments, the KMS Audit DB is adurable queue indicating that the process of requesting a particular keyhas started. In some embodiments, the stored context comprises a clientidentifier, a client certificate, an identifier for the requested key,the type of encryption used, the service associated with the request,the time interval for the release, the use scenario for the release, aunique identifier associated with the request generated in 406 of FIG.4, and any other appropriate data.

In 508, the KMS Engine retrieves an encrypted tenant service key and anencrypted tenant master key. The retrieved encrypted tenant service keycomprises a version of the tenant service key requested by the requestobject encrypted using a tenant master key. The encrypted tenant masterkey is an encrypted version of the key needed to decrypt the encryptedtenant service key. The encrypted tenant master key is encrypted using acustomer key. The encrypted tenant master key must be first decryptedbefore it can be used to decrypt the encrypted tenant service key. Invarious embodiments, different sets of encrypted tenant service keys andencrypted tenant master keys exist for different customers, tenants, andservices. In some embodiments, the two encrypted keys are retrieved froman encrypted key database such as Encrypted Key DB 226 of FIG. 2A. Insome embodiments, the retrieved encrypted tenant service key comprisesEncrypted TSK 228 of FIG. 2A. In some embodiments, the retrievedencrypted tenant master key is Encrypted TMK 227 of FIG. 2A.

In some embodiments, the encrypted keys are cached by the KMS Engine. Ifthe KMS Engine caching policy allows for caching, the KMS Engine willfirst check if a valid encryption key exists in the key cache of KMSEngine before retrieving an encrypted key from the encrypted keydatabase. For example, in the event that a valid encrypted tenant masterkey exists in the key cache of the KMS Engine, the cached key is usedand no encrypted tenant master key is retrieved from the encrypted keydatabase. In some embodiments, the appropriate encrypted tenant masterkey is determined from the context of the request object. In variousembodiments, the appropriate encrypted tenant master key is determinedby metadata associated with the retrieved encrypted tenant service key.

In 510, the KMS Engine generates an unlock request for the encryptedtenant master key. In some embodiments, the unlock request comprises theencrypted tenant master key, the request object, and a request todecrypt the encrypted tenant master key. In some embodiments, the unlockrequest is signed using the private key associated with the keymanagement system. In some embodiments, the unlock request furthercomprises a KMS certificate corresponding to the public key. In someembodiments, the private key associated with the key management systemis the private key associated with KMS Key 225 of FIG. 2A. In someembodiments, if caching of the decrypted tenant master key is enabled,the KMS Engine generates an unlock request requesting key releaseauthorization and transmits the request on the first request of asession; however, upon subsequent requests to decrypt a tenant masterkey during a session uses the cached decrypted tenant master key anddoes not generate or transmit the request to decrypt the tenant masterkey.

In 512, the KMS Engine transmits the unlock request to a key releasesystem. In some embodiments, one or more different key release systemsexist and are accessible to the KMS Engine. In some embodiments, theappropriate key release system is determined by the customer key used toencrypt the encrypted tenant master key. In various embodiments,different key release systems are associated with different customers.In some embodiments, the key release system is key release system 102 ofFIG. 1 and key release system 202 of FIG. 2A. In some embodiments, theunlock message is transmitted from KMS Engine to a key release systemmodule (KRS Module) of the key release system. In some embodiments, theKRS Module comprises KRS Module 232 of FIG. 2A. In various embodiments,the key release system and key management system are connected via anetwork such as Network 206 of FIG. 2A. In some embodiments, thecommunication in 512 relies on an IPSec VPN Tunnel. In some embodiments,the VPN tunnel uses TLS or another secure communication protocoltechnology.

In 514, the KMS Engine receives an unlock response from the key releasesystem. The communication from key release system to KMS Engine occursover a secure protocol. In some embodiments, the communication in 514relies on an IPSec VPN Tunnel using TLS. In some embodiments, the unlockresponse comprises a second encrypted tenant master key and a context ofthe key release. In some embodiments, the second encrypted tenant masterkey is encrypted using the public key of the key management system. Insome embodiments, the public key of the key management system comprisesthe public key of KMS Key 225 of FIG. 2A. In some embodiments, theunlock response is signed using a private key associated with the keyrelease system and the authenticity of the unlock response can beverified by verifying the signature with the corresponding public keyand/or certificate. In some embodiments, the private key associated withthe key release system is the private key associated with KRS Key 233 ofFIG. 2A. In some embodiments, the transition from 512 to 514 isasynchronous and represented by the dotted line in FIG. 5A.

In 516, the KMS Engine decrypts the second encrypted tenant master keyand the encrypted tenant service key. In some embodiments, the secondencrypted tenant master key is decrypted using the private keyassociated with the KMS Engine. In some embodiments, the private keyassociated with the KMS Engine is the private key of KMS Key 225 of FIG.2A. The second encrypted tenant master key is decrypted into a secondunencrypted tenant master key. The encrypted tenant service key isdecrypted using the unencrypted tenant master key into an unencryptedtenant service key.

In 518, the KMS Engine encrypts the unencrypted tenant service key from516 into a second encrypted tenant service key. In some embodiments, thesecond encrypted tenant service key is encrypted using the public keyassociated with the MU that requested the key release. In someembodiments, the public key comprises the public key associated with MUKey 214 of FIG. 2A. In some embodiments, the public key is provided andretained from the request object received in 502 via the public key inthe certificate.

In 520, the KMS Engine determines whether the policy settings requirediscarding keys. In some embodiments, the policy settings are configuredto discard one or more keys received in the unlock response in 514and/or decrypted in 516. The keys stored in the KMS Engine available fordiscarding comprise a second encrypted tenant master key, an unencryptedtenant master key, and an unencrypted tenant service key. In the eventthat the policy settings require discarding the keys, in 522, the KMSEngine purges the appropriate keys. As one example, based on policysettings, the unencrypted tenant service key is immediately removed frommemory. In some embodiments, the memory is overwritten with data toincrease the difficulty of recovering the key from memory.

After the purging of keys is complete or in the event that the policysettings do not require discarding, in 524 the KMS Engine updates thecontext originally logged in 506. In some embodiments, the context isupdated to include a key release authorization. In some embodiments, thecontext is updated to contain the second encrypted tenant service keyfrom 518 and the customer response to the request object. As oneexample, the customer response is based on the unlock response receivedin 514 to the unlock request transmitted to the key release system in512. In some embodiments, the context is stored in an audit or userecord of the key management system audit database. In some embodimentsthe key management system audit database comprises KMS Audit DB 229 ofFIG. 2A.

In 526, the KMS Engine generates a request response. The requestresponse indicates the result of the request for a key release. Therequest response corresponds to the request in the request objectreceived in 502. The request response comprises a unique identifierassociated with the request object. As one example, the uniqueidentifier is a hash of the request context for the service key request.In various embodiments, the unique identifier is used to reference aparticular request object. In some embodiments, the request response issigned with the private key of the key management system and can beverified with the corresponding public key.

In 528, the KMS Engine transmits the request response to its intendedrecipient. In some embodiments, the intended recipient is a user oradministrator of a management utility requesting the key release. Insome embodiments, the request response is emailed to the user oradministrator. In some embodiments, the intended recipient is a softwarecomponent of the management utility requesting the release or a softwareagent for automated processing of the authorization. In otherembodiments, the request response is delivered in an appropriate encodedmessage format such as base 64 encoding.

In 530, the KMS Engine removes the second encrypted tenant service keycreated in 518 from the KMS Audit DB. In some embodiments, the KMSEngine removes the record corresponding to the second encrypted tenantservice key from the KMS Audit DB. In some embodiments, the record isonly modified to remove a released key and not deleted. As one example,the record is modified by removing the second encrypted tenant servicekey from the record and updating it to indicate that the secondencrypted tenant service key is no longer accessible. In someembodiments, 530 is triggered by a message from the KMS API Gateway in414 of FIG. 4 once the second encrypted tenant service key is retrieved.In some embodiments, the transition from 528 to 530 is asynchronous. InFIG. 5A, the transition is represented by the dotted line to reflect theasynchronous nature.

FIG. 5B is a diagram illustrating an embodiment of an unlock requestmessage. In some embodiments, the unlock request message is generated bya key management system and transmitted to a key release system inresponse to receiving a request object. In some embodiments, the unlockrequest message of FIG. 5B is the unlock request generated andtransmitted in FIG. 5A. In some embodiments, the request object isdescribed in FIG. 3B. In the example, an unlock request messagecomprises the key management system certificate, the context associatedwith the requested tenant master key, the request object message, and akey management system signature. In some embodiments, KMS Certificate550 is encoded in base 64 and is the certificate corresponding to KMSKey 225 of FIG. 2A. In some embodiments, KMS Signature 563 is computedusing the private key corresponding KMS Certificate 550. In someembodiments, KMS Signature 563 is a chain signature performed over thereceived request object message combined with a context from the keymanagement system.

In some embodiments, the context associated with the requested tenantmaster key of the unlock request message comprises fields Tenant MasterKey ID 552, Customer Key ID 553, Encrypted Tenant Master Key WithCustomer Key 554, and Initialization Vector 555. In some embodiments,the context contains a tenant master key identifier (e.g., Tenant MasterKey ID 552), a customer key identifier (e.g., Customer Key ID 553), atenant master key encrypted with the customer key (e.g., EncryptedTenant Master Key With Customer Key 554), and an encryptioninitialization vector (e.g., Initialization Vector 555). In someembodiments, the fields Client Certificate 551, Requested Key ID 556,Customer ID 557, Request Time 558, Request Nonce 559, Operation Context560, Operator Comment 561, and Client Signature 562 correspond to fieldsof the request object message described in FIG. 3B.

FIG. 6A is a flow diagram illustrating an embodiment of a process forsecurely storing data. In some embodiments, the process of FIG. 6A isperformed by a key release system (KRS) in response to an unlock requestfrom a key management system. In some embodiments, the process of FIG.6A is performed by the key release system module (KRS Module) of the keyrelease system. In some embodiments, the key release system is keyrelease system 102 of FIG. 1. In some embodiments, the key releasesystem is key release system 202 of FIG. 2A and KRS Module is KRS Module232 of FIG. 2A.

In the example shown, in 602 the KRS Module receives an unlock request.In some embodiments, the unlock request is transmitted from a KMS Engineto the KRS Module from 512 of FIG. 5A. The unlock request providescontext for the requested key release. In some embodiments, the unlockrequest comprises a signature that is verified to ensure the accuracy ofthe request. As described in additional detail in reference to 510 ofFIG. 5A, in some embodiments, the unlock request comprises an encryptedtenant master key, a request object, and a request to decrypt theencrypted tenant master key. In some embodiments, the request objectcomprises the context for the release of the tenant master key.

In 604, the KRS Module evaluates the unlock request to determine whetheror not to release the requested key based on the supplied context. Insome embodiments, the request is evaluated by a human administrator. Insome embodiments, the request is evaluated using a software agent, arules engine, policy settings, or other appropriate means. In 606, it isdetermined whether to approve the release request. In the event therequest is not approved, in 609 the KRS Module handles the rejectedunlock request. In some embodiments, an unlock response rejecting therequest is returned to the KMS Engine. In other embodiments, therejection is logged in a database such as a KRS Audit Database. Invarious embodiments, the customer is notified that a request has beenmade and was rejected. As one example, the customer administratorreceives an email notifying the administrator of all requests includingall rejected requests.

In the event the unlock request is approved, in 608 the KRS Modulegenerates a Hardware Security Module (HSM) request. The HSM requestcomprises a request to decrypt the encrypted tenant master key. In 610,the HSM request is transmitted to the appropriate Hardware SecurityModule (HSM). In some embodiments, the HSM is HSM 236 of FIG. 2A. Insome embodiments, more than one redundant HSM exists. In someembodiments, one or more HSMs are partitioned based on the customer keyseach HSM secures. In some embodiments, the HSM request is transmittedusing a secure protocol. As an example, the KRS Module communicates tothe HSM using TLS.

In 612, the KRS Module receives a HSM response. In some embodiments, theHSM response comprises an unencrypted tenant master key and istransmitted to the KRS Module from a HSM. In some embodiments, the HSMfirst authenticates the HSM request transmitted in 610. Onceauthenticated, the encrypted key in the HSM request is decrypted withthe appropriate encryption key. In some embodiments, the encryption keyis a customer key used to encrypt the encrypted tenant master key. Invarious embodiments, one property of the HSM is that the encryption keynever leaves the HSM. In some embodiments, the customer key is customerkey 238 of FIG. 2A. After the HSM uses the customer key to decrypt theencrypted key provided in the HSM request, the decrypted key is packagedin a HSM response, transmitted to the KRS Module, and received by theKRS Module in 612. In some embodiments, the customer key is a symmetrickey and the same key is used to both encrypt and decrypt. As oneexample, the customer key is an AES-256 secret key generated by a securesource of entropy such as an HSM.

In 614, the KRS Module generates an unlock response. In someembodiments, the unlock response comprises a context associated with theunlock request. The context indicates that the KRS Module has releasedthe tenant master key in response to the unlock request. In someembodiments, the unlock response further comprises a second encryptedtenant master key. The second encrypted tenant master key is theunencrypted tenant master key extracted from the HSM response of 612encrypted with the public key of the key management system. In someembodiments, the unencrypted tenant master key is encrypted with thepublic key of KMS Key 225 of FIG. 2A. In various embodiments, thecontext is signed using a private key. In some embodiments, the privatekey is the private key of KRS Key 233 in FIG. 2A.

In some embodiments, the unencrypted tenant master key is purged frommemory once the second encrypted tenant master key is created. In someembodiments, the memory is overwritten with data to increase thedifficulty of recovering the unencrypted tenant master key from memory.In some embodiments, the purging takes place based on a policy settingand the KRS Module caches certain keys to minimize the number of HSMrequests.

In 616, the KRS Module logs an unlock result. In some embodiments, theunlock result comprises a use and/or authorization record to audit keyreleases. In some embodiments, the unlock result comprises the contextof the unlock request received in 602 and response generated in 614. TheKRS Module logs the unlock result in a database such as a key releasesystem audit database (KRS Audit DB). In some embodiments, KRS Audit DBis KRS Audit DB 234 of FIG. 2A. In various embodiments, the KRS Audit DBstores all access requests and results to key releases. In 618, the KRSModule transmits the unlock response to the KMS Engine. In someembodiments, this transmission is performed over a secure channel usinga protocol such as TLS.

FIG. 6B is a diagram illustrating an embodiment of an unlock responsemessage. In some embodiments, the unlock response message is generatedby a key release system and transmitted to a key management system inresponse to receiving an unlock request message. In some embodiments,the unlock response message of FIG. 6B is the unlock response generatedin 614 and transmitted in 618 of FIG. 6A. In some embodiments, theunlock request message is described in FIG. 5B. In the example, anunlock response message comprises a key release system certificate, thekey request context, and a key release system signature. In someembodiments, the KRS Certificate 650 is encoded in base 64 and is thecertificate corresponding to KRS Key 233 of FIG. 2A. In someembodiments, KRS Signature 659 is computed using the private keycorresponding KRS Certificate 650. In some embodiments, KRS Signature659 is computed using a private key over the header and the base 64encoding of the body of the message. In some embodiments, the privatekey corresponds to the private key of KRS Key 233 of FIG. 2A.

In some embodiments, the key request context of the unlock responsecomprises the context for the key release and the released key. In someembodiments, the key request context comprises the fields Tenant MasterKey ID 651, Encrypted Tenant Master Key With KMS Key 652, Customer ID653, Response Time 654, In Response To Nonce 655, Response Nonce 656, InResponse To Hash 657, and Authorized Key Hash 658. In some embodiments,the key request context contains a tenant master key identifier (e.g.,Tenant Master Key ID 651), a tenant master key encrypted with the KMSpublic key (e.g., Encrypted Tenant Master Key With KMS Key 652), acustomer identifier (e.g., Customer ID 653), a response time (e.g.,Response Time 654), the nonce from the release request (e.g., InResponse To Nonce 655), a newly generated response nonce (e.g., ResponseNonce 656), a response to a hash (e.g., In Response To Hash 657), and anauthorized key hash (e.g., Authorized Key Hash 658).

In some embodiments, Response Time 654 is a use window or an expirationtime for the key release. For example, the message is treated as invalidwhen the current time is outside the response time. In some embodiments,Response Nonce 656 and In Response To Nonce 655 ensure that messagescannot be replayed either to or from the KRS System to initiate orrespond to a given request more than once. In some embodiments, InResponse To Hash 657 increases the certainty that the unlock responsecorrelates in a 1:1 relationship to the original unlock request. InResponse To Hash 657 increases the certainty that the message has notbeen tampered with. In some embodiments, Authorized Key Hash 658prevents the key release from being combined with the use/release ofanother key. In some embodiments, the fields Tenant Master Key ID 651and Customer ID 653 correspond to fields of the unlock request messagedescribed in FIG. 5B.

The techniques described in herein are used to securely store data. Forexample, a customer managing a tenant can use the techniques to cloneand export a data repository that contains data protected by a tenantservice key and customer key. The cloning and exporting operationsrequire that a customer authorize the release of the customer key neededto access the tenant service key. The customer key is needed to decrypta tenant master key. The tenant master key is needed to decrypt thetenant service key. The tenant service key is needed to decrypt theprotected data. In some embodiments, the policy settings can beconfigured such that the KMS engine can enforce renewing a request for akey release for subsequent operations on a protected tenant even whenthe unencrypted key is internally cached inside the key managementsystem. Each initial release and subsequent re-release of a customer keyis logged and can be audited.

Automated Tenant Operations

In some embodiments, the key release functionality is automated. In someembodiments, the automation is accomplished by integrating aself-service ticketing system to find appropriate grantedauthorizations. In some embodiments, the self-service ticketing systemis accessible over a network such as the Internet. In this scenario, themanagement utility makes a call to a self-service ticketing system priorto contacting the key management system. In some embodiments, themanagement utility generates a request context, which is signed with aprivate key, and transmits the request to the self-service ticketingsystem. In some embodiments, the management utility observes the stateof a ticket system to determine what tenant operations have beenpreviously requested before transmitting a similar request. In someembodiments, the request is performed by MU 212 of FIG. 2A.

In some embodiments, when configured with a self-service ticketingsystem, the key release system no longer requires a human administratorto evaluate an unlock request. In the scenario, KRS Module evaluates theunlock request to determine whether or not to release the requested keyby verifying the state of the self-service ticket system to confirm thekey has been authorized for release. In some embodiments, the evaluationis performed by KRS Module 232 of FIG. 2A by communicating over anetwork to a self-service ticketing system.

In some automated embodiments, once the key management system hasupdated the Audit database to reflect the release of the requestedtenant service key, the KMS Engine transmits the encrypted tenantservice key to the KMS API Gateway. The KMS API Gateway in turntransmits the encrypted tenant service key to the system requesting thekey release (e.g., a management utility), where it is used to performsecure data operations. In some embodiments, the encrypted tenantservice key is pushed to the management utility; the key is not storedin the KMS Audit database and not requested by the management utilityvia a confirmation request.

Auditing of Key Releases

FIG. 7A is a flow diagram illustrating an embodiment of a process forauditing key releases. In some embodiments, the process of FIG. 7A isperformed by the system in FIG. 1 and the system in FIG. 2A. In theexample shown, a key release system and a key management system bothkeep an audit log of key releases. In some embodiments, the audit logsare stored as key use/authorization audit records in audit databases. Insome embodiments, the key release system audit database (KRS Audit DB)is KRS Audit DB 234 of FIG. 2A and the key management system auditdatabase (KMS Audit DB) is KMS Audit DB 229 of FIG. 2A.

In the example shown, in 702, audit records corresponding to keyreleases are retrieved from the KMS Audit DB. In 704, audit recordscorresponding to key releases are retrieved from the KRS Audit DB. In706, the audit records from the KMS Audit DB and KRS Audit DB arecompared. Each authorized key release is logged in both the KMS Audit DBand the KRS Audit DB. In some embodiments all records are retrieved andcompared. In some embodiments, only failed or only successful keyreleases are retrieved and compared. In some embodiments, the recordsare compared by determining if any records exist in one audit log butnot the other. One example is the case that the records in the two auditdatabases are inconsistent and do not match. A record exists in oneaudit database indicating a completed key release but no matching recordexists in the other database. In 708, it is determined whether the auditlogs match and are consistent. In some embodiments, each compared fieldof the record must be identical to the corresponding field of the recordin the other database for the audit logs to match.

In the event the logs do not match, in 710 the audit discrepancy ishandled. In some embodiments, the discrepancy indicates a configurationproblem, software bug, connectivity issue, or malicious event has causedthe release of a key without both modules' full understanding. Forexample, a release record in the KRS Audit DB that is missing the KMSAudit DB warrants further investigation and can indicate that thecustomer released a key but that the key was not used by the softwareapplication requesting the key. In some embodiments, the discrepancyinitiates a tamper evident kill switch for all processing. No furtherkeys are released until the kill switch is disabled. In someembodiments, the discrepancy initiates sending a discrepancy auditmessage to the user or administrator of the secure storage system. Insome embodiments, the discrepancy prompts the user or administrator witha warning to investigate the issue before additional processingcontinues.

In the event the two audit logs do match and are consistent, in 712 nodiscrepancy is found. In some embodiments, in 712 a successful auditmessage is sent to the user or administrator of the secure storagesystem.

In some embodiments, the audit process is run periodically, for example,hourly, daily, based on the frequency of key releases, or based onanother appropriate metric. In some embodiments, the process is runafter each key release by the key release system. In some embodiments,the process is run after each key release by the key management system.In some embodiments, the process is initiated by the management utilityor the user or administrator of the management utility of the securestorage system. In some embodiments, the process of FIG. 7A is performedby one or more Audit Agents including a KMS Audit Agent and a KRS AuditAgent. In some embodiments, the key management system comprises a KMSAudit Agent. In some embodiments, the key release system comprises a KRSAudit Agent. In some embodiments, a KMS Audit Agent is a KMS Audit Agent244 of FIG. 2A and KRS Audit Agent is KRS Audit Agent 254 of FIG. 2A.

FIG. 7B is table illustrating an embodiment of a release record. In someembodiments, the release record is a database record used to log thecontext associated with a release request and used for auditing key useand authorization. In some embodiments, the release record is generatedas the context for a release. In some embodiments, the release record islogged in 506 and 524 of FIG. 5A as part of the log context. In someembodiments, the release record is logged in 616 of FIG. 6A as part ofthe unlock result. In some embodiments, the release records areretrieved in 702 and 704 and compared in 706 of FIG. 7A. In someembodiments, the release record are consistent with database schemasshown in FIG. 8B and FIG. 8C. In some embodiments, the release recordcorresponds to a record in table Key Usage 811 of FIG. 8B and/or arecord in table Access Audit History 821 of FIG. 8C.

In the example shown, a release record comprises fields Request ID 722,Request Context Message Hash 724, Customer Authorization Message 726,and Customer Authorization Message Hash 728. Request ID 722 is a requestidentifier. Request Context Message Hash 724 is a hash of the requestcontext. Customer Authorization Message 726 is a customer authorizationmessage for a key release. Customer Authorization Message Hash 728 is ahash of the customer authorization message. In some embodiments, valuefor Request Context Message Hash 724 is generated in 406 of FIG. 4 aspart of the request reply and acts as a confirmation of the receipt of akey release.

FIG. 8A is diagram illustrating an embodiment of a KMS Encrypted KeyDatabase schema. In some embodiments, the schema of FIG. 8A is used forthe encrypted key database of the key management system. In someembodiments, Encrypted Key DB 226 of FIG. 2A uses the schema of FIG. 8A.In the example, the KMS Encryption Key Database schema comprises tablesTenant Master Key 801, Tenant Service Key 802, Customer KRS 803,Customer 804, Tenant 805, and Service 806. The type of connection shownin FIG. 8A between tables 801, 802, 803, 804, 805, and 806 indicates therelationship between tables, for example, multiple lines merging into asingle line indicates a many-to-one relationship. In some embodiments,the tables 801-806 will comprise additional fields as appropriate.

In some embodiments, each record of table Tenant Master Key 801corresponds to an encrypted tenant master key for a customer. Eachrecord contains an identifier for the tenant master key (e.g.,MasterKeyId), a customer identifier (e.g., CustomerId), the encryptedtenant master key (e.g., TMKCipherText), an initialization vector (e.g.,iv), a customer enveloped with key identifier (e.g.,CustomerEnvelopedWithKeyId) indicating the id of the Customer Master Keyused to encrypt the Tenant Master Key, an encrypted by KRS identifier(e.g., EncryptedByKRSId) indicating which KRS system holds the CustomerMaster Key referenced by CustomerEnvelopedWithKeyId, and a tenantidentifier (e.g., TenantId).

In some embodiments, each record of table Tenant Service Key 802corresponds to an encrypted tenant service key for a tenant. Each recordcontains a key identifier for the tenant service key (e.g., KeyId), atenant master key identifier matching the key used for enveloping (e.g.,MasterKeyId), the encrypted tenant service key (e.g., TSK CipherText),an initialization vector (e.g., iv), and a service identifier (e.g.,ServiceId).

In some embodiments, each record of table Customer KRS 803 correspondsto a customer key release system. Each record contains a networklocation of a key release system (e.g., CustomerKRSURI), a publiccertificate for the key release system (e.g., CustomerPubCert), and acustomer identifier (e.g., CustomerId).

In some embodiments, each record of table Customer 804 corresponds to acustomer. Each record contains a customer identifier (e.g., CustomerId)and the name of the customer (e.g., customerName). In some embodiments,each record of table Tenant 805 corresponds to a tenant for a customer.Each record contains a tenant identifier (e.g., TenantId), the name ofthe tenant (e.g., tenantName), and a customer identifier for the tenant(e.g., CustomerId). In some embodiments, each record of table Service806 corresponds to a service offered for a tenant. Each record containsa service identifier (e.g., ServiceId), the type of service (e.g.,serviceType), and a description for the service (e.g., ServiceDesc).

FIG. 8B is diagram illustrating an embodiment of a KMS Audit LogDatabase schema. In some embodiments, the schema of FIG. 8B is used forthe audit database of the key management system. In some embodiments,KMS Audit DB 229 of FIG. 2A uses the schema of FIG. 8B. In the example,the KMS Audit Log Database schema comprises tables Key Usage 811,Customer 812, Authorized Access To 813, Tenant Service Key 814, andTenant Master Key 815. The type of connection shown in FIG. 8B betweentables 811, 812, 813, 814, and 815 indicates the relationship betweentables, for example, multiple lines merging into a single line indicatesa many-to-one relationship. In some embodiments, the tables 811-815 willcomprise additional fields as appropriate.

In some embodiments, each record of table Key Usage 811 corresponds to akey release request and use. Each record contains the informationassociated with a key release request, including the context of a keyrelease request (e.g., RequestContextMsg), a request time of the request(e.g., RequestTime), a request identifier (e.g., RequestId), and a hashof the request context message (e.g., RequestContextMsgHash). Eachrecord also contains information associated with the authorization ofthe key release, including a customer authorization message (e.g.,CustomerAuthorizationMsg), a customer authorization message identifier(e.g., CustomerAuthorizationMsgId), and a hash of the customerauthorization message (e.g., CustomerAuthorizationMsgHash). Each recordfurther contains an identifier for the tenant service key for theauthorized service (e.g., AuthorizedServiceKeyId), an identifier for theunlocked tenant master key used to encrypt the tenant service key (e.g.,UnlockedMasterKeyId), a customer identifier (e.g., CustomerId), andinformation of the authorized requester (e.g., AuthorizedRequester).

In some embodiments, each record of table Customer 812 corresponds tothe customer that a key release was request from. Each record contains acustomer identifier (e.g., CustomerId). In some embodiments, each recordof table Authorized Access To 813 corresponds to the information relatedto the key requested. Each record contains a key identifier (e.g.,KeyId) and a request identifier (e.g., RequestId). In some embodiments,each record of table Tenant Service Key 814 corresponds to theinformation related to the tenant service key requested. Each recordcontains a key identifier (e.g., KeyId). In some embodiments, eachrecord of table Tenant Master Key 815 corresponds to the informationrelated to the tenant master key needed to decrypt the requested tenantservice key. Each record contains a key identifier (e.g., KeyId).

FIG. 8C is diagram illustrating an embodiment of a KRS Audit LogDatabase schema. In some embodiments, the schema of FIG. 8C is used forthe audit database of the key release system. In some embodiments, KRSAudit DB 234 of FIG. 2A uses the schema of FIG. 8C. In the example, theKRS Audit Log Database schema comprises tables Access Audit History 821and Authorization Agent 822. The type of connection shown in FIG. 8Cbetween tables 821 and 822 indicates the relationship between tables,for example, multiple lines from table 821 merging into a single line attable 822 indicates a many-to-one relationship. In some embodiments, thetables 821 and 822 will comprise additional fields as appropriate.

In some embodiments, each record of table Access Audit History 821corresponds to a key release request and access. Each record containsthe information associated with a key release request, including thecontext of a key release request (e.g., RequestContextMsg), a requesttime of the request (e.g., RequestTime), a request identifier (e.g.,RequestId), and a hash of the request context message (e.g.,RequestContextMsgHash). Each record also contains information associatedwith the authorization of the key release, including a customerauthorization message (e.g., CustomerAuthorizationMsg), a customerauthorization message identifier (e.g., CustomerAuthorizationMsgId), anda hash of the customer authorization message (e.g.,CustomerAuthorizationMsgHash). Each record further contains anidentifier for the unlocked tenant master key (e.g.,UnlockedMasterKeyId) and an identifier of the customer approval agent(e.g., CustomerApprovalAgentId). In some embodiments, each record oftable Authorization Agent 822 corresponds to the information related tothe authorization agent. Each record contains an agent identifier (e.g.,AgentId) and a description of the agent (e.g., AgentDesc).

Cardinality of Customers to Tenants to Services

Using the described techniques herein, in some embodiments, the processfor securely storing data is scaled to multiple customers and redundancyis incorporated to improve reliability and speed among other factors. Insome embodiments, multiple HSM Clusters are accessible by a key releasemodule, and each customer will have one customer key per HSM Cluster.Each customer can have one or more tenants, and each tenant associatedwith a customer has a unique tenant master key. Each tenant master keyis secured by enveloping it with a customer key. For example, a customerkey is used to encrypt each tenant master key owned by a customer. Foreach tenant, one or more tenant service keys exist. For example, eachtenant service key is enveloped by a tenant master key.

In some embodiments, a master key is shared across different tenants fora customer. This non-tenanted master key is at the same level in theenveloping hierarchy as a tenant master key but is not specific to aparticular customer's tenant. The non-tenanted master key is envelopedby the customer key and each tenant service key is enveloped by thenon-tenanted master key. In some embodiments, more than one master keyis shared across different tenants for a customer.

Caching Keys

In some embodiments, the KMS Engine is capable of caching an unencryptedtenant master key at the KMS Engine. In some embodiments, the KMS Engineis KMS Engine 224 in FIG. 2A. In the event the policy setting directsthe KMS Engine to cache an unencrypted tenant master key in memory, theKMS Engine will generate an unlock request without including theencrypted tenant master key. The unlock request generates a key releaseapproval by the key release system which is logged as an unlock resultin the KRS Audit Database. No encrypted tenant key is transmitted to theKRS Module and no HSM request is generated. In this configuration, thesecurity of the process is improved by not transmitting key material inthe protocol between the key management system and the key releasesystem. An audit trail is maintained by specifying a unique identifierfor the requested release of a tenant master key and logging the keyrelease authorization.

In some embodiments, the KMS Engine caches a second encrypted tenantmaster key encrypted with the public key of the KMS Engine instead of anunencrypted tenant master key. The second encrypted tenant master keycan be decrypted by the KMS Engine without transmitting the key to thekey release system. In this scenario, no unencrypted tenant master keysare cached at the KMS Engine.

Public/Private Key Pairs

In the technology described herein, various public/private key pairs areused, for example, public/private keys are used to validate requests andresponses. In some embodiments, the private key resides securely in theappropriate module and only the public key is accessible outside themodule. In some embodiments, MU Key 214, KMS Key 225, and KRS Key 233are RSA public/private key pairs. For example, the public keycorresponding to a private/public key pair is publicly accessible andcan be validated using a trusted certificate authority or out of bandpre-exchange of public keys. In some embodiments, a public key in theform of a certificate is included in messages, such as the initialrequest object, passed between networked components. In variousembodiments, the messages sent between modules, such as between themanagement utility and KMS API Gateway; between the KMS API Gateway andKMS Engine; between the KMS Engine and KRS Module; between the KMSEngine and user/administrator of the management utility; between the KMSEngine and the management utility; and between any other appropriatemodules are signed using a private key and verified using thecorresponding public key.

Symmetric Keys

In the technology described herein, various symmetric keys are relied onfor symmetric encryption and for enveloping keys. In some embodiments,customer key, tenant master key, and tenant service keys are symmetrickeys. In some embodiments, Customer Key 238, Encrypted TMK 227, andEncrypted TSK 228 are symmetric keys. As one example, customer key (orcustomer enveloping key) is the top level key stored in a HSM. The HSMcan be managed by the software as a service provider, the customer, or athird-party. The customer key never leaves the HSM and is used toperform encrypt/decrypt operations on child keys that it protects. Insome embodiments, the keys are AES-256 secret keys using GCM or EAX modeciphers and generated by a secure source of entropy such as an HSM. Asanother example, tenant master key is the top level key per tenant andis used to encrypt/decrypt all tenant service keys for that tenant. Insome embodiments, the tenant master key is encrypted multiple times bydifferent parent keys such that if one key cannot be reached, anothercan be used to decrypt the tenant master key. As another example, tenantservice key is the secret key used to encrypt data that a particularservice owns. Each tenant service key is encrypted by the tenant masterkey when stored in the key management system encrypted key database.

Key Rotation

In the technology described herein, the use of multiple enveloping keysincluding a customer key, tenant master key, and tenant service key,provides for multiple types of key rotations. In many instances, when akey is changed, only a subset of the keys must be rotated. In someembodiments, a key is rotated based on schedule, demand, when a key hasbeen compromised, when administration change occurs, data migration, orany other appropriate reason.

In the event of a customer key rotation, each tenant master key for theparticular customer is decrypted using the old customer key andencrypted using the new customer enveloping key. Rotating a customer keyrequires access to a HSM. If redundant HSMs are configured then rotationrequires access to all HSMs storing the customer key. In someembodiments, when customer key rotation occurs, the current customer keyK1 is rotated to a new customer key K2. The new customer key K2 ismarked as the current customer key. The key release system will honorrequests for K1 but extends the unlock response to include both K1 andK2. In some embodiments, the request for K1 is honored for apre-configured period of time. In response to receiving an unlockresponse with two keys K1 and K2, the key management system isresponsible for updating the tenant master key by enveloping it with newcustomer key K2. In some embodiments, once the tenant master key hasbeen encrypted using K2, the rotation is complete.

In some embodiments, if a customer key has been rotated, the unlockresponse from the key release system comprises additional fields. Insome embodiments, the additional fields comprise the customer keyidentifier of the new customer key, the requested tenant master keyencrypted with the new customer key, and an initialization vector forencryption. Upon receipt of the new fields, the key management system isresponsible for updating the stored encrypted tenant master key, thecustomer key version number, and the initialization vector values.

In the event of a tenant master key rotation, each tenant service keyfor the particular tenant is decrypted using the old tenant master keyand encrypted using a new tenant master key. In some embodiments, thenumber of tenant service keys is bound by the number of servicesprovided. Rotating a tenant master key requires access to a HSM todecrypt the encrypted old tenant master key, generating a new tenantmaster key, and access to the HSM to encrypt the newly generated tenantmaster key. In some embodiments multiple HSMs exist and are accessed. Insome embodiments, the newly generated tenant master key is firstencrypted using the public key of the key release system and thentransmitted to the key release system. The key release system decryptsthe newly generated tenant master key using its private key and encryptsit using a HSM and customer key. The newly encrypted tenant master keyenveloped with the customer key is received by the key management systemwhere it is stored in an encrypted key database.

In some embodiments, on rotation of a tenant master key, the key releaserequest comprises an indication that the request is for key rotation. Asone example, the request object includes a field “operation” that is setto “decryptForPeriodicRotation”. In some embodiments, key releases forkey rotation are automated and bypass a requirement that a humanadministrator release the key. For example, for key rotations, a keyrelease system provides automatic approval instead of pending approvalby a human administrator to release the key. In some embodiments, therequest object includes a field “operation” that is set to“decryptForEmergencyRotation” and used to differentiate an emergencyrotation. In some embodiments, emergency rotations are automaticallyapproved without authorization from a human administrator. In someembodiments, the customer receives a notification on key rotation. Forexample, a customer receives a signed email after an emergency keyrotation.

In the event of an individual tenant service key rotation, the tenantservice key for the particular tenant is decrypted using the tenantmaster key and a new tenant service key is created and encrypted usingthe tenant master key. The tenant master key is decrypted using a HSMand the customer key by initiating a key release. In some embodiments,on rotation of a tenant service key, the key release request comprisesan indication that the request is for tenant service rotation. As oneexample, the request object includes a field “operation” that is set to“decryptForTSKCreation” for creation of a tenant service key and set to“decryptForTSKRotation” for rotation of a tenant service key. In someembodiments, when an operation is a paused or halted, an authorizedrelease for the tenant service key expires. The tenant service key mustbe re-unlocked to continue operations on data protected by the key.

In some embodiments, tenant service key rotation is implemented by theservice that operates on the secure data repository. In someembodiments, the key management system engine will periodically, basedon policy and/or configuration, generate a new tenant service key toinitiate key rotation. The new tenant service key is marked as thecurrent version of the key. Services that rely on the tenant service keywill acknowledge the key has been updated and begin to rotate the oldtenant service key for the new tenant service key.

In the case of a security incident, for example, when one or more keysare compromised, all keys may need to be rotated at all layers at once.In some embodiments, the rotation begins at the top of the key chainwith the customer key, completing with the tenant service key. In someembodiments, the complete rotation requires coordinating with allcustomers to initiate the immediate rotation of keys.

Audit Verification

In some embodiments, a private blockchain is used to indicate that allparticipants in the system and transactions are verified and known usingthe issuance of certificates/public key infrastructure. Participants inthe system (KMS and KRS) agree to each proposed addition by mutuallysigning a next block added to the blockchain. A copy of the privateblockchain is stored in FIG. 2A KMS audit DB 229 and KRS audit DB 234.In some embodiments, a blockchain comprises a set of underlying datastructures (e.g., Merkle trees, hash chains, etc.) and protocols (e.g.,a communication protocol—for example, gossip) that enable verificationof occurrence of one or more transactions for audit purposes and foragreement among distributed system participants. In some embodiments, aprivate blockchain system allows only specific named parties to write tothe blockchain, unlike a public blockchain (e.g., BitCoin's blockchain)which allows any party to write to the blockchain. In some embodiments,a private blockchain allows writing to the blockchain using trustedcertificate. In some embodiments, a private blockchain allows otherparties (e.g., parties without trusted certificates) to verify and/orother parties to read the blockchain. In some embodiments, no workfactor is required for writing to the blockchain enabling high speedauditing of key management transactions. In some embodiments, a publicblockchain has artificial slowness (using the work factor) built in todeter double spending of coins (and other issues). In some embodiments,a private blockchain system uses public blockchain system datastructures for key management audit needs.

FIG. 9 is a flow diagram illustrating an embodiment of a process foraudit records. In some embodiments, the process of FIG. 9 is used fortransaction audit records stored by KRS Audit Agent 254 in KRS audit DB234 or by KMS Audit Agent 244 in KMS audit DB 229 in FIG. 2A. In theexample shown, in 900 an indication is received of an action taken. Forexample an action taken may comprise one or more of the following: a keyrequest by the KMS, a consumption of a released key by the KMS, a keyreleased by the KMS, a key released by the KRS, or any other appropriateaction. In 902, a KMS Audit Agent or KRS Audit Agent will use theirPrivate Key to cryptographically sign over the contents of a transactionusing RSA SHA256 or equivalent algorithm. For example, the KMS AuditAgent or the KRS Audit Agent generates a signed transaction auditrecord, as appropriate. In some embodiments, signing a transactioncomprises using a private key and a message content and a signingalgorithm to produce a signature. In some embodiments, a signatureverifying algorithm is able to accept or reject the message contentgiven the signature and the public key associated with the private keyused for producing the signature. In 904, transaction audit record isstored in the local transaction pool. For example, the transaction auditrecord is stored in a transaction pool in the Audit DB in the KMS systemor the KRS system Audit DB. In 906, transaction audit record is sent viaa communication protocol to all known audit agents in Secure StorageSystem. For example, the transaction audit record is sent to the KMSAudit Agent from the KRS Audit Agent or from the KRS Audit Agent to theKMS Audit Agent. In various embodiments, the communication protocolcomprises a gossip protocol, a Paxos protocol, a Raft protocol, or anyother appropriate protocol. In some embodiments, the communicationsprotocol used for making the other nodes of a distributed system awareof a change that has occurred.

In some embodiments, a transaction has a format as follows:

{ “operation”: “release”, “ctx”: “requested”, “ts”:millisTimestamp, } .EncodedSignatureBytesB64UrlSafe

FIG. 10 is a flow diagram illustrating an embodiment of a process foraudit records. In some embodiments, the process of FIG. 10 is used fortransaction audit records stored by KRS Audit Agent 254 in KRS audit DB234 or by KMS Audit Agent 244 in KMS audit DB 229 in FIG. 2A. In theexample shown, in 1000 transactions accumulated are examined. Forexample, the transaction audit records in a transaction pool of the KMSAudit DB or the KRS Audit DB are examined. In some embodiments, atransaction pool stores a number of transaction audit records. In 1002,the signatures of the transactions are verified. For example, thesignatures of the transaction audit records stored in the transactionpool of the KMS Audit DB or the KRS Audit DB are verified by performinga signature verification using the known public key of the creator ofthe transaction. For example, a Key Release Request made by the KMSEngine will be signed with the Private Key of KMS, and either the KRSAudit Agent or the KMS Audit Agent can use the shared, knowncorresponding Public Key of KMS to verify the transaction signatureusing the RSA SHA256 signature verification algorithm. In 1004,transactions with valid signatures are accepted and stored in the localAudit DB. For example, in the event that the transaction signature isverified, the transaction associated with the signature is indicated asvalid. In 1006, the transactions are grouped by request ID for completesets. For example, transactions that are part of a complete setaccording to a request identifier (ID) are grouped together. In 1008, aMerkle tree is generated. For example, a request key transaction, arelease key transaction, and a consume key transaction are grouped byrequest identifier (e.g., as associated with a request to store data ora request to retrieve data) and are hashed and stored in a Merkle tree.In some embodiments, a Merkle tree is a tree in which every non-leafnode is labeled with the hash of the labels or values (in case ofleaves) of its child nodes. Merkle trees allow efficient and secureverification of the contents of large data structures. Merkle trees area generalization of hash lists and hash chains. Key consumption is anaudited action performed by the KMS Engine indicating what it did withthe key it asked the KRS Module for. For example, the KMS Engine firstrequests KRS Module to decrypt the Tenant Master Key, KRS then releasesthe decrypted TMK, and finally the KMS Engine messages the KMS Auditagent to generate an audit record that it consumed/used the TMK todecrypt a TSK. This final leg of the audit flow is important because a3^(rd) party attacker who intercepted or prevented the decrypted TMKfrom being returned, or the KMS Engine performing an unexpected actionwith the TMK could both be conditions to halt processing in the systemsand cause a re-key, audit and/or investigation. In 1010, a proposedblock is signed by the audit agent responsible for building theblockchain. In this model, only one audit agent, either in KMS or theKRS is designated at the block proposer/leader at any time. For example,a block associated with the Merkle tree is signed by the KMS Audit Agentand then the KRS Audit Agent using a private key (e.g.,cryptographically signing). In some embodiments, the proposed block isgenerated using the Merkle tree. In 1012, a counter signed block isreceived. For example, a request is made to counter sign the proposedblock, the signed block is transmitted to another system (e.g., from theKMS Audit Agent to the KRS Audit Agent or vice versa) and is verifiedand counter signed and the counter signed proposed block transmittedback. In 1014, the block is added to the blockchain. For example, theblock is added to the local blockchain. This exchange should result inthe KMS Audit DB and the KRS Audit DB eventually having identical copiesof the signed blockchain at some point in time.

In some embodiments, both the KMS and KRS audit agents are able to seewhether transactions in their local transaction pool ever made it intothe blockchain. In some embodiments, each participant (e.g., KMS and KRSaudit agents, etc.) validates their copy of the blockchain. In someembodiments, verification of hashes and signatures protecting the chainensures that no data has been altered or removed. In some embodiments,verification comprises cryptographic verification, where eachparticipant's audit agent periodically traverses the local copy of theblockchain stored in the local Audit DB and computes each hash to theroot of the chain. In some embodiments, when either the KMS Audit Agentin response to the KRS Audit Agent or visa versa, provides countersignature on a proposed block, it must validate the chain. In the eventthat a node has been removed or altered, the local verification failsand the proposed block is not counter signed. In some embodiments, wheneither the KMS Audit Agent or KRS Audit Agent provides an initialsignature, it must validate the chain. In the event that a node has beenremoved or altered, a newly proposed end block will not match theblockchain and the proposed block is not signed. In some embodiments,the transaction is published on a public blockchain by the blockchainleader audit agent. Publishing text to a public blockchain furtherallows each participant to trust the other is acting as expected, aswell as opens the key exchange to audit by other participants asdesired. In various embodiments, the privacy of the transaction ispreserved even when publishing by publishing a transaction id and/orsystem id and/or checksum in place of publishing actual transactiondetails. In some embodiments, transaction details are encrypted by asymmetric key known to both the KMS and the KRS before writing to theblockchain (e.g., a public blockchain) to further obscure transactiondetails. In some embodiments, a hash of the local block in the LeaderAudit DB is written to the blockchain (e.g., a public blockchain), alongwith the block id to further obscure transaction details.

FIG. 11 is a flow diagram illustrating an embodiment of a process foraudit records. In some embodiments, the process of FIG. 11 is used toprovide a counter signed block received in 1012 of FIG. 10. In theexample shown, in 1100 signatures of transactions are verified. Forexample, transactions of the block or blockchain local to the KMS AuditDB or the KRS Audit DB are verified. In 1102, the proposed block iscounter signed. For example, in the event that the transactionsignatures are verified, the proposed block is counter signed. In 1104,the counter signed block is sent. For example, the counter signed blockis sent to the original audit agent. For example, KRS Audit Agentcounter signs the block KMS Audit Agent wants to publish, and sends itback to KMS Audit Agent for addition to the copy of the blockchain theKMS Audit DB holds.

FIG. 12 is a flow diagram illustrating an embodiment of a process foraudit records. In some embodiments, the process of FIG. 12 is used fortransaction audit records stored by KRS Audit Agent 254 in KRS audit DB234 or by KMS Audit Agent 244 in KMS audit DB 229 in FIG. 2A. In theexample shown, in 1200 a next transaction is selected. In 1202, it isdetermined whether the transaction is N minutes old with no block entry.For example, it is determined whether the transaction has existed for asystem configured time period (e.g., N minutes) without beingincorporated into the local private blockchain. In the event that thetransaction is not N minutes old with no blockchain id entry, controlpasses to 1200. In the event that the transaction is N minutes old withno block entry, control passes to 1204. In 1204, it is indicated tosuspend processing, and the process ends.

FIG. 13 is a block diagram illustrating an embodiment of a blockchain.In some embodiments, the blockchain of FIG. 13 is used in 1014 of FIG.10. In the example shown, genesis block 1300 is self-referential. Insome embodiments, a genesis block is the first block of a blockchain. Insome embodiments, the genesis block is hardcoded into system software.In some embodiments, the genesis block does not reference a previousblock. In some embodiments, a blockchain data structure comprises achain of blocks in which a block of the blockchain points to a previousblock using a hash. In some embodiments, the genesis block hashes overitself. Block 1032 points to genesis block 1300. Block 1302 includesmrkl_root as root mrkl hash, nonce as random1, hash as hash gen block,signatureA as over block, and signature as over block. Block 1034 pointsto genesis block 1302. Block 1304 includes mrkl_root as root mrkl hash,nonce as random2, hash as hash gen block, signatureA as over block, andsignature as over block.

FIG. 14 is a block diagram illustrating an embodiment of a Merkle tree.In some embodiments, the Merkle tree of FIG. 14 is generated using 1008of FIG. 10. In the example shown, a Merkle tree is based at least inpart on one or more of the following: a request key transaction, arelease key transaction, a consume key transaction, or any otherappropriate transaction. In various embodiments, the key associated withthe transaction that is used for the Merkle tree comprises one or moreof the following: a tenant service key, a tenant master key, a customerkey, or any other appropriate key. In the example shown, request key txn1412 points to hash 0-0 1406 that is generated by hashing request keytxn. Release key txn 1414 points to hash 0-1 1408 that is generated byhashing release key txn. Consume key txn 1416 points to hash 1-0 1410that is generated by hashing consume key txn. Hash 0 1402 is generatedby combining hash 0-0 1406 and hash 0-1 1408. In some embodiments, thecombining of hash 0-0 1406 and hash 0-1 1408 comprises hashing hash 0-01406 and hash 0-1 1408. Hash 1 1404 is generated from hash 1-0 1410. Insome embodiments, the generating from hash 1-0 1410 comprises hashinghash 1-0 1410. Root hash 1400 is generated by combining hash 0 1402 andhash 1 1404. In some embodiments, the generating from hash 0 1402 andhash 1 1404 by hashing hash 0 1402 and hash 1 1404.

Although the foregoing embodiments have been described in some detailfor purposes of clarity of understanding, the invention is not limitedto the details provided. There are many alternative ways of implementingthe invention. The disclosed embodiments are illustrative and notrestrictive.

What is claimed is:
 1. A system for secure storage of data comprising: akey database; a processor configured to: receive a request object thatindicates a nature of a tenant service key request; retrieve anencrypted tenant service key and a first encrypted tenant master keyfrom the key database; transmit an unlock request to a key releasesystem, wherein the unlock request includes a request for the firstencrypted tenant master key; receive an unlock response from the keyrelease system, wherein the unlock response includes a second encryptedtenant master key; decrypt the second encrypted tenant master key andthe encrypted tenant service key; and encrypt, using the decryptedsecond tenant master key, the decrypted tenant service key to create asecond encrypted tenant service key.
 2. The system of claim 1, whereinthe decrypting of the second encrypted tenant master key and theencrypted tenant service key is performed using a private key.
 3. Thesystem of claim 1, wherein the encrypting of the unencrypted tenantservice key to the second encrypted tenant service key is performedusing a public key.
 4. The system of claim 1, wherein the retrievedencrypted tenant service key comprises a version of the tenant servicekey requested by the request object encrypted using a first tenantmaster key.
 5. The system of claim 1, wherein the unlock requestincludes the first encrypted tenant master key, the request object, anda request to decrypt the first encrypted tenant master key.
 6. Thesystem of claim 1, wherein the unlock response is a signed using aprivate key associated with the key release system.
 7. The system ofclaim 1, wherein the processor is further configured to: verify therequest object be verifying a signature of the request object.
 8. Thesystem of claim 1, wherein the processor is further configured to: log acontext to the key database.
 9. The system of claim 1, wherein theprocessor is further configured to: transmit a request response to anintended recipient.
 10. A method for secure storage of data comprising:receiving a request object that indicates a nature of a tenant servicekey request; retrieving an encrypted tenant service key and a firstencrypted tenant master key from a key database, wherein the retrievedencrypted tenant service key comprises a version of the tenant servicekey requested by the request object encrypted using a first tenantmaster key; transmitting an unlock request to a key release system,wherein the unlock request includes a request for the first encryptedtenant master key; receiving an unlock response from the key releasesystem, wherein the unlock response includes a second encrypted tenantmaster key; decrypting the second encrypted tenant master key and theencrypted tenant service key; and encrypting, using the decrypted secondtenant master key, the decrypted tenant service key to create a secondencrypted tenant service key.
 11. The method of claim 9, wherein thedecrypting of the second encrypted tenant master key and the encryptedtenant service key is performed using a private key.
 12. The method ofclaim 9, wherein the encrypting of the unencrypted tenant service key tothe second encrypted tenant service key is performed using a public key.13. The method of claim 9, wherein the retrieved encrypted tenantservice key comprises a version of the tenant service key requested bythe request object encrypted using a first tenant master key.
 14. Themethod of claim 9, wherein the unlock request includes the firstencrypted tenant master key, the request object, and a request todecrypt the first encrypted tenant master key.
 15. The method of claim9, wherein the unlock response is a signed using a private keyassociated with the key release system.
 16. The method of claim 9,further comprising: verifying the request object be verifying asignature of the request object.
 17. The method of claim 9, furthercomprising: logging a context to the key database.
 18. The method ofclaim 9, further comprising: transmitting a request response to anintended recipient.
 19. A computer program product for securely storingdata, the computer program product being embodied in a non-transitorycomputer readable storage medium and comprising computer instructionsfor: receiving a request object that indicates a nature of a tenantservice key request; retrieving an encrypted tenant service key and afirst encrypted tenant master key from a key database, wherein theretrieved encrypted tenant service key comprises a version of the tenantservice key requested by the request object encrypted using a firsttenant master key; transmitting an unlock request to a key releasesystem, wherein the unlock request includes a request for the firstencrypted tenant master key; receiving an unlock response from the keyrelease system, wherein the unlock response includes a second encryptedtenant master key; decrypting the second encrypted tenant master key andthe encrypted tenant service key; and encrypting, using the decryptedsecond tenant master key, the decrypted tenant service key to create asecond encrypted tenant service key.